Brake systems are exposed to and require protection from numerous elements, such as, for example weather. Existing brake systems typically are of hydraulic methodology and require large amounts of pressure within the system to operate. Anti-lock brake systems are becoming more prevalent throughout the industry and require an additional amount of pressure within the system to function properly. Additionally, certain weather condition, such as, for example extreme cold can degrade hydraulic performance and require additional amounts of pressure to be available within the system for the system to function as designed.
Typically, brake systems employ vacuum boosters to provide an amplification of force within the system. Existing vacuum booster technology utilizes some form of engine vacuum to create a pressure differential across one or more diaphragms to provide a pressure differential and thus, load amplification. This phenomenon can take place in both single, and tandem vacuum boosters, in which there may be one or two working chambers. Unfortunately, this configuration is limited to an increase of approximately fifteen (15) pounds per square inch (psi) of vacuum that is then converted into output force. The force is converted to hydraulic pressure by the master cylinder. In certain conditions, such as the weather conditions mentioned above, the response of the system pressure can be delayed significantly due to the increase, in viscosity and other frictional factors.
A conventional solution to the aforementioned problem has been to introduce a secondary pump, also referred to as a pre-charge pump, to the system to improve the system response. Unfortunately, the inclusion of a pre-charge pump within the system entails the use of additional hydraulic lines and the addition of a separate port from the system reservoir to provide fluid to the vacuum side of the pre-charge pump.
Additionally, although pre-charge pumps provide needed additional pressure there is an amount of time required to provide the additional pressure, called a response time, or subsequent requirements for pressure. Unfortunately, anti-lock brake systems generally have a requirement for pressure to be delivered very quickly and frequently. The advent of anti-lock brake systems has generated a need create a system that can provide additional system pressure delivered in a quick and frequent manner.
It would be desirable, therefore, to provide a system that would overcome these and other disadvantages.